A Nashville school district plans to be the first in the nation to use facial recognition cameras for security. The technology uses cameras to measure and identify a person's major facial features, much like the device used to train students at Pellissippi State, seen in the pictures and video with this story. If the cameras detect an unfamiliar face or identify someone barred from the school, an alarm sounds.Three Nashville schools and an administrative building will be equipped with the cameras next month.A few police departments in Virginia and Florida have already tried the technology and dropped its use, after they said it failed to spot wanted criminals.